Unseasonal cold blast hits New Zealand ahead of summer, significant storm expected

Unseasonal cold blast hits New Zealand ahead of summer, significant storm expected

An unexpected cold blast and snowstorm hit the lower South Island, New Zealand on Sunday, November 5, 2017, just three weeks out from summer. Thick snow started falling at around 09:30 local time, blanketing the Crown Range between Queenstown and Wanaka. An even colder blast is forecast for the rest of the week and forecasters are urging motorists to keep an eye on weather warnings.

"Unusually severe weather is expected to affect much of the South Island and lower North Island later Tuesday, November 7 and into the first half of Wednesday, November 8 and associated severe weather Warnings and Watches are now in force for many areas," Met Service said.

This event is expected to cause significant disruption to travel and is likely to damage infrastructure such as power lines and roads.

Also, bitterly cold southwesterlies are expected to sweep north over the lower South Island overnight Tuesday into early Wednesday morning, bringing a period of brief heavy snow to relatively low levels and may cause stress to livestock, the service warns.

Early Wednesday, a deep and intense low is expected to move over the central South Island, bringing widespread severe gales and heavy rain, before the system moves away to the southeast. There is high confidence that wind speeds will reach warning criteria in exposed places over the South Island north of Otago and Fiordland and over the lower North Island from Taranaki across to south of Hawkes Bay southwards, and moderate confidence over the remainder of the North Island. Also, there is moderate confidence that rainfall accumulations will reach warning amounts in Buller, the western ranges of Nelson and the Richmond Range including the Rai Valley in Marlborough.

Also early Wednesday, an unseasonably cold southwesterly flow is expected to sweep north over the lower South Island. This could bring significant amounts of snow to low levels in a brief period. There is low confidence of snowfall accumulations reaching warning amounts above 400 m (1 312 feet) in Canterbury south of Christchurch, Otago, Southland and Fiordland. The cold winds and snow could cause stress to livestock, may affect infrastructure such as power lines and affect some of the higher passes and roads in this area. Note, there is also low confidence of brief heavy rain for eastern Otago early Wednesday morning as depicted on the chart below:

Severe weather outlook - New Zealand

Later on Wednesday, a front is forecast to move quickly east across the North Island and to deliver a period of brief heavy rain as it moves through. There is low confidence that short duration heavy rain warnings will be required for parts of the North Island excluding the east coast from Gisborne to Wairarapa.

From Thursday through Saturday, a ridge of high pressure is forecast to build over central and southern New Zealand. However, a moist easterly flow is forecast to spread southwards over the upper North Island during Friday and Saturday, with low confidence of warning amounts of rain for Northland, eastern parts of the Rodney District and Coromandel Peninsula during Friday and Saturday, then low confidence for Gisborne and the Wairoa District on Saturday.

Featured image: Snowstorm hits South Island, New Zealand on November 5, 2017. Credit: NewsHub

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